gpu: Add the ability to wait on upload completion.

gpu/command_buffer/client/gles2_implementation.cc

Index: gpu/command_buffer/client/gles2_implementation.cc
diff --git a/gpu/command_buffer/client/gles2_implementation.cc b/gpu/command_buffer/client/gles2_implementation.cc
index 600c02f3751a2ab72eed498be7ee0f02e628130d..e19911c81705b831b8e470ad5a0eb025afb46a0d 100644
--- a/gpu/command_buffer/client/gles2_implementation.cc
+++ b/gpu/command_buffer/client/gles2_implementation.cc
@@ -3439,6 +3439,14 @@ void GLES2Implementation::AsyncTexSubImage2DCHROMIUM(
   return;
 }
 
+void GLES2Implementation::WaitAsyncTexImage2DCHROMIUM(GLenum target) {
+  GPU_CLIENT_SINGLE_THREAD_CHECK();
+  GPU_CLIENT_LOG("[" << GetLogPrefix() << "] glWaitAsyncTexImage2DCHROMIUM("
+      << GLES2Util::GetStringTextureTarget(target) << ")");
+  helper_->WaitAsyncTexImage2DCHROMIUM(target);
+  CheckGLError();
+}
+
 // Include the auto-generated part of this file. We split this because it means
 // we can easily edit the non-auto generated parts right here in this file
 // instead of having to edit some template or the code generator.